#include <iostream>

template<typename T>
const T pi = 3.1415326;

template<typename T1,typename T2>
struct Test
{
    T1 a;
    T2 b;
};
template<typename T>
using B = Test<int,T>;//简化特化写法

int main()
{
    std::cout<< pi<int> <<std::endl;
    std::cout<< pi<double> <<std::endl;
    B<double> b;
    b.a;
    b.b;
    return 0;
}